Yarn feeder

ABSTRACT

A yarn feeder (F) including a holding device (H) for holding a yarn braking body in an extension arm (2, 2a) of a housing, a support body (6a) for a holder (5) of the yarn braking body (4) and a moving drive including a cylindrical piston (6b) which is movable in a cylinder (7) to move the yarn braking body (4) between a braking position and a gap position relative to a storage body (3) of the yarn feeder (F). The piston (6b) is arranged as an integrated guide element of the support body (6a) on the support body (6a). At least one guide nose (9) which engages into a guide track (10) fixed onto the extension arm is provided as a rotation preventing member on the piston and/or on the support body at a transverse distance from the piston axis (X).

FIELD OF THE INVENTION

The present invention relates to a yarn feeder having a movable yarnbraking body for braking yarn.

BACKGROUND OF THE INVENTION

In a yarn feeder which is known from EP 0 446 447 A1, the support bodyis a movable slide which is movable in the extension arm by means of acompressed-air/cylinder/piston unit. A spring is accommodated in thecylinder and acts on the piston in a direction opposite to thecompressed-air action. The piston rod is coupled via a hinge to anadjusting screw which has fixed thereon the movable slide which issupported in the guide tracks of the extension arm and separated fromthe piston. The movable slide guides the holder of the yarn braking bodywhich is adjustable by means of an adjusting screw relative to themovable slide. Great constructional efforts are required for guiding themovable slide in the extension arm and the holder on the movable slide.The strong soiling caused by depositing yarn material, the relativelygreat reactive forces of the support of the yarn braking body on thestorage body, which slightly vibrates during operation, unavoidable wearin the various guide tracks, the multipart structure of the holdingdevice and the necessity of an easy adjustability of the yarn brakingbody with an exactly reproducible braking position might lead toproblems because of which the gap position and/or the braking positioncannot be adjusted in the predetermined manner. Furthermore, theversatile holding device requires considerable constructional space.

It is the object of the present invention to provide a yarn feeder ofthe above-mentioned type in which the holding device is simple undermanufacturing and assembling aspects and is only composed of a few partsand can guarantee the predetermined position of the yarn braking body ina reliable manner in the case of both frequent and rare adjustingoperations.

SUMMARY OF THE INVENTION

This object is achieved by the yarn feeder of the invention whichincludes a guide on one of a piston and a support body and a guide trackon an extension arm.

The holding device is simple under manufacturing (industrial scalemanufacture) and assembling aspects and is robust during operation. Itis only composed of a few parts and requires relatively litteconstructional space (compact design). There is a very stable and exactguiding and positioning of the yarn braking body by the piston and bythe guide nose which acts as a rotation preventing means, with thereaction forces being transmitted over a large surface and over aconsiderable length and with advantageous lever arms into the extensionarm. The yarn braking body can be easily adjusted over long servicelives. Predetermined positions of the yarn braking body are reliablyreached at frequent and rare adjustment cycles. The holding device canbe used in a universal manner and without any significant modificationsin yarn feeders in which an automatic adjustment (action on the pistonby compressed air) takes place for yarn threading and for changing theyarn braking body, and also in yarn feeders in which only a manualadjustment is desired. In the manually operated version the piston has adominant guiding function, the guide portion of the piston in thecylinder being well protected against soiling, while the piston in theautomatic version additionally assumes a drive function. It may beprovided with one or several seals, if necessary. However, it is alsopossible to use material combinations with self-lubricating properties,e.g. a Teflon cover of the piston and/or the cylinder. The piston formsa unit with the support body with respect to stable guidance andmounting of the yarn braking body. Nevertheless, it might happen thatthe piston must be produced as a separate component and fixedlyconnected to the support body.

Production is simplified and there is an exact guiding of the yarnbraking body thanks to an integral design of the cylinder in theextension arm.

The embodiment where an integrally molded member defines the piston andsupport body is advantageous from a manufacturing point of view. Inparticular for production on an industrial scale, injection molding is asuitable technique for ensuring highly accurate shapes and dimensions.

In the invention yarn feeder, the piston is guided by a spring to therespective braking position of the yarn braking body which has beenadjusted with an adjusting screw. The holder need no longer be adjustedrelative to the support body and guided during said operation, but takesthe position which has been predetermined for it by the support body andwhich is defined by the position of the adjusting screw nut and can bevaried, if desired. The spring can also be used for adjusting thebraking position. As a positive side effect, the holder can rapidly beadjusted by hand relative to the spring without the adjusting screwhaving to be shifted at the same time. To save further parts, the springand the adjusting screw nut could, however, be omitted in a simplifiedversion and the adjusting screw could directly be screwed into thepiston.

A stable, in particular broad, support is obtained by providing thepiston and adjusting screw on one side and the guide nose on the otherside of a central axial plane of the yarn braking body and extensionarm. Constructional space is saved in radial direction, based on theaxis of the storage body, and a compact design of the holding device isaccomplished. Enough space is created for further components of the yarnfeeder to be accommodated in the extension arm, for instance, sensors orthe like.

The embodiment where the piston is tubular is constructionally simple.

By another feature of the invention, rotational locking and axialmovability of the adjusting screw nut are achieved in a constructionallysimple manner through the cross-section of the tubular section.

In the embodiment where the spring surrounds the adjusting screw, anadvantageously long spring can be accommodated without additionalconstructional space being wasted. The long, centrally accommodatedspring ensures that the yarn braking body is always reliably returnedinto the braking position again. The adjusting sleeve permits a manuallyeffected movement of the yarn braking body, for instance for adjustingthe gap position for threading a yarn or for replacing the yarn brakingbody.

The embodiment in which the yarn braking body is adjusted by rotatingthe adjusting sleeve, is constructionally simple, robust and reliable infunction. The necessary rotary lift of the adjusting sleeve, the movinglift of the yarn braking body and the adjusting force can bepredetermined by the shape and length of the guide groove. It ispossible to mount the coupling element on the adjusting sleeve and tomold the guide groove into the rotary mount in the extension arm.

A uniform adjustment is possible where at least one end of the guidegroove has a blocking section. The blocking section expediently providedfor at one or both ends of the guide groove makes it possible to blockthe adjusting sleeve in such a manner that it is immovably held underthe action of an axial force only. It is expedient to design therespective transition from the guide groove into the blocking section ina stepped manner, so that one can clearly feel at the turning handle ofthe adjusting sleeve that or whether the coupling element has enteredinto the blocking section.

The adjusting screw can easily be operated where a head of the adjustingscrew has a turning knob with a rotary lock. The rotary lock permits asensitively controlled rotation of the adjusting screw and preventseither the adjusting screw or the adjusting sleeve from rotatingindependently.

In the embodiment where the holder is pivotally supported, a pivotalmovement of the yarn braking body is possible. The rotary pin is solidlysupported.

An automatic adjustment of the yarn braking body into the gap positionmay be provided by the action of compressed air. The resetting operationis then carried out by the spring acting on the piston. The adjustingscrew is not moved along with the adjusting movement because theadjusting screw nut is displaced in the piston. This contributes to asmall motional resistance. In the case of a manually operable design thecompressed-air supply enables the air displaced by the piston under theaction of the spring to espace with little resistance.

The embodiment wherein an intercepting device is provided is especiallyexpedient. Whenever the yarn braking body is fixed in the gap orexchange position and does not unintentionally return into the brakingposition again by mistake under the action of the spring or possiblyeven under the pneumatic actuation of the piston at a decreasingpressure.

The variant wherein the intercepting device comprises an engaging anddisengaging element must be manipulated manually for engaging and/ordisengaging the intercepting device, whereas in the embodiment of claim16 it is solely the intercepting device which is engaged or released bythe movement of the yarn braking body. It is only necessary to move theyarn braking body into the desired position (by hand or by means of apneumatic actuation of the piston) in order to engage the interceptingdevice. A release of the intercepting device requires a slight furthermovement (by hand or by pneumatic actuation of the piston) before thespring will return the yarn braking body into the braking position.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the subject matter of the invention shall now beexplained with reference to the drawing, in which:

FIG. 1 is a longitudinal section through a yarn feeder comprising aholding device for a yarn braking body;

FIG. 2 is a front view of the yarn feeder of FIG. 1;

FIG. 3 is a longitudinal section through another embodiment of a yarnfeeder; and

FIG. 4 is a detail section in the plane of axis 11 in FIGS. 1 and 3.

DETAILED DESCRIPTION

FIGS. 1-4 show two embodiments of yarn feeders F, each provided with aholding device H for a yarn braking body 4, wherein components whichhave the same function, but differ from one another in appearance andsize are provided with the same reference numerals.

In the yarn feeder F of FIGS. 1 and 2, a housing 1 has arranged thereonan extension arm 2 with an extension arm end member 2a which extendsalong the outer circumference of a storage body 3 approximately inparallel with the longitudinal axis thereof beyond the storage body 3and away from the housing 1. A yarn braking body 4 of an annular yarnbrake B, which body is shown in its braking position in FIG. 1,cooperates in the customary manner with the storage body 3. The yarnbraking body 4 is arranged, in a manner which is not shown in detail, ona holder 5 which (FIG. 2) is fork-shaped and supported in a support body6a. The holder 5 is either fixedly connected to the support body 6a or(FIG. 1) is fixedly connected to the support body 6 in the longitudinaldirection of extension arm 2, 2a and is pivotable about an axis 11 whichis approximately radial relative to the storage body 3. The support body6a has preferably integrally connected thereto a cylindrical piston 6bwhich projects from support body 6a towards housing 1 and is movablyguided in a cylinder 7 integrally formed in extension arm 2, 2a.Cylinder 7 includes a compressed-air supply 8 to which a source ofcompressed air can be connected, if necessary.

A guide nose 9 which engages into a longitudinally extending guide 10 ofthe extension arm is provided on support body 6a and/or on piston 6b ata distance from piston axis X. It would also be possible to provide theguide nose 9 in the extension arm and to let the guide nose engage aguide of the support body 6a or of the piston 6b.

According to FIG. 2 the piston axis X is arranged at a side of a centralplane M of the brake body 4 whereas the guide nose 9 and thelongitudinal guide 10 are located at the other side of this centralplane. This results in a guide which needs little constructional spacein radial direction and is used for guiding the yarn braking body withadvantageous lever arms relative to the central plane M.

The piston 6b has a tubular shape and is provided on the inside with atransverse wall which forms an axial stop 12. The transverse wall isprovided with a bore which is passed through by a threaded section 15 ofan adjusting screw 13. A tubular section 17 of the piston 6b is adaptedwith its cross-section to the circumferential configuration of anadjusting screw nut 16 which is secured against rotation in the tubularsection 17, but made movable in the direction of piston axis X. Adampening and sealing O-ring 18 can be provided between the adjustingscrew nut 16 and the axial stop 12. At the other side of the axial stop12, there is supported a biased coil spring 19 which passes through thesupport body 6a, penetrates into piston 6b and rests in the embodimentof FIG. 1 with its other end on an adjusting sleeve 21 which supportsthe adjusting screw 14. The adjusting sleeve 21 is coaxially rotatablerelative to piston axis X in a rotary mount 20 of the extension arm endmember 2a and projects with an enlarged head portion 22 to the outside.A handle 23 for rotating or turning the adjusting sleeve 21 is providedon the head portion 22. A head 14 of the adjusting screw 13 is held in aturning knob 27 which is knurled and supported on the head portion 22with a rotary lock 28 being interposed. The rotary lock 28 contains, forinstance, a spring-loaded locking member which cooperates with lockingrecesses provided in the head portion 22.

The adjusting sleeve 21 is provided on its outer circumference with atleast one inclined, for instance, thread-like guide groove 25 which isbordered at both ends and which is engaged by a coupling element 24which is designed as a pin and disposed in the extension arm end member2a. The guide groove 25 is expediently provided at both ends withblocking sections 25a which extend in rotational direction and which arerespectively entered into by the coupling element 24 when an axialdisplacement of the adjusting sleeve 21 under an axial pressure is to beruled out. The adjusting screw 13 is rotatably supported in theadjusting sleeve 21 and carries a retaining element R across which thereaction force of the yarn braking body 4 is transmitted to theadjusting sleeve 21 and from said sleeve to the coupling element 24 andthe extension arm 2, 2a.

The extension arm end member 2a contains an enlarged wall 30 (FIG. 2)and a yarn eyelet 29 coaxial to the axis of the storage body. The endmember 2a is secured at 31 to the extension arm 2.

The cross-section of the support body 6a with the piston 6b moldedthereon and with the guide nose 9 can schematically be seen in FIG. 4.The piston 6b with the axial stop 12 is located at one side of axis 11or the central plane M whereas the guide nose 9 is molded onto theopposite side.

A bore 35 serves to receive a pivot pin for pivotally mounting theholder 5 on support body 6a, as will later be explained with referenceto FIG. 3.

In FIG. 1 the yarn braking body 5 is in the braking position in which itis axially pressed at a predetermined axial force onto the storage body3. This position is either defined by the adjusting screw nut which isstopped on the axial stop 12 or, even more expediently, by theequilibrium of forces between the resilient reaction force of the yarnbraking body 4 and the force of spring 19. When the axial stop 12 restson the adjusting screw nut 16 in the position of FIG. 1, the piston 6bcan be shifted further to the left by unscrewing the adjusting screw 13by means of the turning knob 27 so as to increase the contact pressureof the yarn braking body. By contrast, when the adjusting screw 13 istightened, the piston 6b is pulled further to the right via theadjusting screw nut 16 to reduce the contact pressure of the yarnbraking body 4.

To move the yarn braking body 4 into a gap position with respect to thestorage body 3, for instance, in order to thread a yarn or to replacethe yarn braking body 4, the turning handle 22 is operated and theadjusting sleeve 21 is rotated so that thanks to the engagement of thecoupling element 24 the adjusting sleeve 21 is pulled in FIG. 1 to theright, carrying along the adjusting screw 13 via the turning knob 27,with the adjusting screw 13, in turn, transferring the piston 6b withthe support body 6a and the yarn braking body 4 into the gap positionvia the adjusting screw nut 16. The course of the guide groove 25 may besuch that there will be an automatic locking action and any desiredposition of the yarn braking body 4 will be maintained automatically.However, it is also possible to rotate the adjusting sleeve 21 to suchan extent, expediently over about half a rotation, that the couplingelement 24 enters into the blocking section 25a at the left side. Toreturn the yarn braking body 4 into the braking position the turninghandle 23 is operated in the other direction, and the adjusting sleeve21 is again moved into the position shown in FIG. 1.

The yarn feeder F according to FIG. 1 can be retrofitted for anautomatic adjustment of the yarn braking body 4, if necessary. To thisend the compressed-air supply 8 has connected thereto a source ofcompressed air which upon activation acts on piston 6b and displaces thepiston 6b against the force of spring 19 up to the stop on the adjustingsleeve 21 at the most. The adjusting screw 13 maintains its position;the adjusting screw nut 16 is displaced in the tubular section 17. Whenthe pressure applied to piston 6b is reduced, spring 19 will press thepiston 6b and thus the support body 6a and the yarn braking body 4 backinto the braking position again. To gain more space for the replacementof the yarn braking body, the adjusting sleeve 21 may also be rotated,as mentioned above.

The embodiment of the yarn feeder F according to FIG. 3 comprises aholding device H which may be of an automatic type (thanks to the actionof compressed air on the piston 6b from the connection member 8ainserted into the compressed-air supply 8) and may also be designed fora manual adjustment (by a hand acting on holder 5). A cover cap 6c isadditionally provided in piston 6b. A counter nut 16a is mouted on theadjusting screw 13. The adjusting screw 13 is fixed in the end member 2aof the extension arm 2 by means of the retaining element R (for instancea snap ring) in an axially immovable, but rotatable manner. The turningknob 27 cooperates with an end face of end member 2a which is providedat the right side and has molded therein locking recesses for the rotarylock 28. The spring 19 is supported with its right end directly on acounter-face 32 of the end member 2a. The holder 5 is pivotable with apivot pin 33 in the support body 6a and about the axis 11.

In addition, there may be provided an intercepting device C forintercepting, against the force of spring 19, the support body 6a withthe piston 6b in a gap or exchange position adjusted by action on thepiston 6b or by pulling on holder 5. As for the intercepting device C, amanually operable engaging or disengaging element 34 can be seen whichactivates an intercepting element (not shown) which can be engagedagainst spring loading or disengaged under spring load and which gripsbehind a stop (not shown) of the support body 6a.

The intercepting device C is expediently designed such that it becomesoperative by pressing on the engaging element 34 as soon as the yarnbraking body 4 has reached the gap or exchange position. Theintercepting element (not shown) is again disengaged by a renewedmovement, either by action on the piston 6b or by manual pulling onholder 5, and the engaging and disengaging element 34 is again broughtinto the illustrated position.

The support body 6a with its integrally molded piston 6b of FIG. 3 isshown in FIG. 4 in a section in the plane of axis 11. The bore 35 servesto support the pivot pin 33. A shoulder for engaging the interceptingdevice C is drawn in broken line at 36. The guide nose 9 engages intothe guide 10 of the extension arm 2 at the side of the central plane Mopposite to the piston axis X so as to achieve lever arms which are asgreat as possible for guiding and supporting the yarn braking body 4.

Instead of the manually operable intercepting device C, an automaticallyacting intercepting device in the manner of a ratchet mechanism or anindexing means could be provided in the yarn feeder according to FIG. 3(but also in the yarn feeder F according to FIG. 1), the automaticallyacting intercepting device becoming operative and retaining the supportbody 6a in the gap or exchange position of the yarn braking body 4whenever the unit consisting of support body 6a and piston 6b has beenadjusted to a correspondingly great extent. To release the automaticintercepting device, the unit consisting of support body 6a and piston6b must be further moved in the same direction of movement, forinstance, by renewed action on piston 6b or by pulling on holder 5 inFIG. 3 to the right in order to release the intercepting deviceautomatically. In such a case the yarn braking body 4 will returnautomatically into the braking position again under the action of spring19.

In the embodiment of FIG. 1, the spring 19 and the adjusting screw nut16 could be omitted, provided the adjusting screw 13 is directly screwedwith its threaded section 15 into the transverse wall of the piston 6bwhich forms the axial stop 12. In such a case, however, it would nolonger be possible to adjust the yarn braking body 4 by simply pullingon holder 5 and the piston 6b could also no longer be acted uponpneumatically.

The unit consisting of support body 6a and piston 6b is technicallyadvantageous under manufacturing aspects because it is possible withrelatively small efforts to achieve a neat engagement between cylinder 7and piston 6b and an anti-rotational locking substantially without anyplay due to the engagement of the guide nose 9 into the guide 10 of theextension arm. The cooperation between the cylindrical piston 6b and thealso cylindrical cylinder 7, which is integrally molded into theextension arm 2, can be controlled easily, just like the cooperationbetween guide nose 9 and guide 10, i.e. without any substantial wear andabove all without any danger arising from malfunctions caused bydepositing impurities, such as yarn material, dust and lint which arebound to be encountered in such a yarn feeder to a great degree.Furthermore, the assembly is simple, since it is only the piston whichhas to be introduced into the cylinder, and the guide nose into theguide. In the embodiment of FIG. 1, the adjusting sleeve 21 with theadjusting screw 13 and the screwed-on piston 6b with the support body 6acan be prefabricated. The holder 5 is then mounted through an openingfrom above in the extension arm 2 on support body 6a.

We claim:
 1. In a yarn feeder comprising a storage body for storing ayarn thereon, a housing, and a holding device having an annular yarnbraking body which surrounds said storage body for braking said yarnduring removal from said storage drum, said holding device beingarranged in an extension arm of said housing and comprising a supportbody which is linearly movably guided in said extension arm forsupporting a holder of said yarn braking body, said yarn feeder furtherincluding a support-body moving drive having a cylindrical piston whichis movable in a cylinder along a piston axis to move said yarn brakingbody between a braking position and at least one gap position, said gapposition being adjustable by said moving drive, comprising theimprovement wherein said piston is arranged on said support body andforms an integrated guide element of said support body, a fixed guidetrack being provided on said extension arm wherein said guide track isdisposed a transverse distance from said piston axis, one of said pistonand said support body including at least one guide nose which engagesinto said guide track and prevents rotation of said support body aboutsaid piston axis.
 2. The yarn feeder according to claim 1, wherein saidcylinder is integrally formed in said extension arm.
 3. The yarn feederaccording to claim 1, wherein said support body and said piston aredefined by an integrally molded member.
 4. The yarn feeder according toclaim 3, wherein said molded member is formed of metal or plastics. 5.The yarn feeder according to claim 1, wherein said holder is fixedlymounted on said support body in an adjusting direction, an adjustingscrew being provided which is rotatable in said extension arm andsupported in the adjusting direction relative to said extension arm andwhich engages into said piston, said piston including an axial stopwhich is fixed thereon, an adjusting screw nut being provided which ismovable relative to said piston and is secured against rotation in saidpiston, a spring being provided which acts on and biases said adjustingscrew nut towards said axial stop.
 6. The yarn feeder according to claim5, wherein said piston and said adjusting screw are arranged at one sideand said guide nose at the other side of a central axial plane of saidyarn braking body and said extension arm.
 7. The yarn feeder accordingto claim 6, wherein said piston is made tubular and provided with atransverse wall which forms said axial stop, said spring penetratingfrom behind into said piston and being supported on said transversewall.
 8. The yarn feeder according to claim 5, wherein a tubular sectionof said piston is provided as a space of movement for said adjustingscrew, said tubular section having a cross-section which is adapted tothe circumferential configuration on said adjusting screw nut.
 9. Theyarn feeder according to claim 5, wherein said spring surrounds saidadjusting screw and is supported at an end facing away from said axialstop, said spring being supported directly in said extension arm. 10.The yarn feeder according to claim 5, wherein said spring surrounds saidadjusting screw and is supported at an end facing away from said axialstop, said spring being supported on an adjusting sleeve which isaxially and manually movable in said extension arm and in which saidadjusting screw is supported in an axially immovable manner.
 11. Theyarn feeder according to claim 10, wherein said adjusting sleeve isarranged in a rotary mount of said extension arm which is coaxial tosaid piston axis, said adjusting sleeve including a turning handle whichis accessible from outside of said yarn feeder and is provided in thearea of said rotary mount with an axially defined guide groove, saidguide groove being inclined relative to the rotational direction, acoupling element being provided which engages into said guide groove andis retained in said extension arm such that turning of said turninghandle axially displaces said adjusting sleeve.
 12. The yarn feederaccording to claim 11, wherein said guide groove is provided at at leastone end with the blocking section extending approximately in therotational direction to prevent axial displacement of said adjustingsleeve.
 13. The yarn feeder according to claim 5, wherein a head of saidadjusting screw is inserted into a turning nut which is seated at thefree end of said extension arm directly, said turning nut including arotary lock which prevents rotation thereof.
 14. The yarn feederaccording to claim 5, wherein a head of said adjusting screw is insertedinto a turning nut which is seated on a head portion of said adjustingsleeve, said turning nut including a rotary lock which prevents rotationthereof.
 15. The yarn feeder according to claim 5, wherein saidextension arm has arranged therein an intersecting device defining saidgap position of said yarn braking body for intersecting said yarnbraking body adjusted against said spring, said intersecting deviceacting on one of said piston and said support body against the operativedirection of said spring.
 16. The yarn feeder according to claim 15,wherein said intersecting device comprises a manually operable engagingand disengaging element which is accessible from outside of saidextension arm.
 17. The yarn feeder according to claim 16, wherein saidintersecting device is spring-loaded.
 18. The yarn feeder according toclaim 15, wherein said intersecting device can automatically be engagedand disengaged by the adjusting motion of said yarn braking body. 19.The yarn feeder according to claim 1, wherein said holder of said yarnbraking body is patentably supported in said support body with a rotarypin located in a central axial plane of said yarn braking body and saidextension arm.
 20. The yarn feeder according to claim 1, wherein saidcylinder comprises a compressed-air supply.